The present invention relates to deprocessing of semiconductor devices and more particularly to a method and system for removing conductive lines, particularly copper lines.
A semiconductor device includes circuitry formed on a semiconductor die. The circuitry in the semiconductor device includes conductive lines. An insulator, such as an interlayer dielectric, typically separates conductive lines in a layer of the semiconductor device. Conductive lines typically include a conductive layer and a barrier layer. In conventional semiconductor devices, the conductive layers are formed of aluminum. In some current semiconductor devices, however, the conductive layers are formed using copper. The barrier layer is provided in order to isolate the conductive layer from a remaining portion of the semiconductor device.
In order to determine locations of faults in the circuitry or otherwise investigate the semiconductor device, deprocessing is performed. Deprocessing removes successive layers of the semiconductor device. After each layer is removed, the remaining portion of the semiconductor device can be investigated.
During deprocessing of the semiconductor device, the conductive lines are removed. The conductive layer is typically etched. The barrier layer is then removed. The insulator is then removed. The remaining portion of the semiconductor device can then be investigated.
Although the conventional method for removing the conductive lines functions, it may be difficult to find a selective etchant that will easily remove the conductive layer. Even if an etchant which can remove the conductive layer can be found, the etchant may also over etch the remaining portions of the semiconductor device. Thus, portions of the semiconductor devices desired to be kept intact for further investigation may be inadvertently removed. Accordingly, what is needed is an alternate system and method for selectively removing conductive lines. The present invention addresses such a need.
The present invention provides a method and system for removing a conductive line from a semiconductor device. The semiconductor device includes-a barrier layer separating the conductive layer from a portion of the semiconductor device. The method and system comprises exposing a portion of the barrier layer, etching the barrier layer after the barrier layer has been exposed, and lifting off the conductive layer after the barrier layer has been etched.
According to the system and method disclosed herein, the present invention provides a method for removing a conductive line, thereby increasing overall system performance.